Dental X-Rays Explained: Types, Frequency and Safety

Key takeaways

• X-rays show what a visual exam cannot: decay between teeth and under fillings, infection at root tips, and the supporting bone.
• Bitewings find cavities between back teeth, periapicals show a whole tooth, and a panoramic image shows both jaws.
• How often you need them depends on your risk of decay, not a fixed calendar.
• The dose is very small, and pregnancy is no reason to delay an X-ray needed to diagnose a problem.

Why dentists take X-rays (what a visual exam misses)

A clinical exam with a mirror, light and gentle probe shows only visible surfaces. Much of what matters is hidden: the contact points between back teeth, the tooth under a filling or crown, the roots and the surrounding bone. Early decay there rarely hurts, and enamel can look intact while a lesion spreads beneath it.

X-rays (radiographs) fill that gap. They help a dentist find decay before it reaches the nerve, measure bone levels in gum disease, spot infection at a root tip, follow developing teeth in children and plan extractions, root canals or implants. At a routine check-up they should be taken only when the result is likely to change your care.

Periapical X-rays: one tooth, root to tip

A periapical ("around the root tip") X-ray shows one or two teeth along their full length, from the biting edge past the end of the root into the surrounding bone. It is the image a dentist reaches for when a specific tooth hurts, has been knocked or has a deep filling. It can reveal an abscess or bone loss at the root tip, a fractured root, deep decay approaching the pulp and the shape of the root canals. Periapicals are also taken during and after root canal treatment to check the canals are filled to the right length.

Bitewing X-rays and cavities between teeth

Bitewings are the workhorse of routine check-ups. You bite on a small tab holding the sensor, and the image shows the upper and lower back teeth together and the bone between them, but not the root tips.

Their main job is finding cavities between teeth. These hide because decay starts at the contact point, beneath smooth enamel that neither a mirror nor floss can see through, and an early lesion usually causes no symptoms. On a bitewing the decay appears as a darker shadow in the enamel or the dentine underneath, showing how deep it has gone.

Depth drives treatment. An early lesion confined to the enamel can often be stopped with fluoride varnish, better cleaning and less frequent sugar, then watched on later X-rays. Once decay has reached the dentine and formed a cavity, a small tooth-coloured filling is usually needed; the dental fillings guide compares materials and costs. Left longer, decay can reach the pulp and need root canal treatment, or a crown if damage is extensive. Daily cleaning with floss or interdental brushes, plus fluoride toothpaste, is the main prevention.

Panoramic X-rays: the whole-jaw overview

A panoramic X-ray (often called an OPG) is taken by a machine that rotates around your head while you keep still for several seconds. It produces one wide image of all the teeth, both jaws, the jaw joints and the sinuses.

It is useful for assessing wisdom teeth, checking developing teeth, looking for cysts or other jaw changes, and as a starting point for orthodontic or implant planning. Its detail is lower than a bitewing's, so it does not replace bitewings for small cavities. There is no fixed schedule: it is taken when a specific question needs answering. Where a three-dimensional view is needed, a dentist may request a cone-beam CT scan, which involves a higher dose and is used selectively.

How dentists combine methods to detect cavities

No single test finds every cavity, so dentists layer several:

• Visual inspection with good light and dried teeth, looking for chalky white spots, brown or grey shadows and breakdown at the edges of old fillings.
• Gentle probing, because pressing hard on a softened early lesion can damage it.
• Bitewing X-rays for the surfaces between back teeth.
• Transillumination, shining a bright light through the tooth so decay shows as a shadow, with no radiation.
• Laser fluorescence devices, which give a reading that helps monitor suspicious grooves over time.

The results are read with your history: recent cavities, a dry mouth, frequent snacking and receding gums all make it more likely that a shadow is active decay.

How often you need X-rays: a risk-based schedule

There is no one-size-fits-all interval. The selection criteria published by the American Dental Association (ADA) with the US Food and Drug Administration (FDA) time routine bitewings by each patient's risk of decay:

For children, bitewings are advised only when the surfaces between the teeth cannot be checked by eye or with a probe. New adult patients usually get an individualised set: bitewings with a panoramic view or selected periapicals, or a full-mouth series where there is widespread disease or a long treatment history. Outside these schedules, X-rays are taken whenever needed to diagnose pain, swelling or an injury, or to plan surgery.

Radiation dose: what the numbers mean

According to RadiologyInfo.org, published by the Radiological Society of North America and the American College of Radiology, a dental X-ray taken inside the mouth, such as a bitewing, gives an effective dose of about 0.005 mSv, roughly one day of natural background radiation. A panoramic X-ray is about 0.025 mSv, around three days. For context, the ADA notes that dental imaging accounts for less than 1 per cent of the estimated collective annual dose from medical imaging in the United States.

The principle is to keep exposure as low as reasonably achievable: only images that will change care, fast digital receptors, a beam narrowed to the area examined, and no avoidable retakes. In 2024 the ADA stopped recommending lead aprons and thyroid collars for patients: shields can block the image and force a retake, and a narrowed beam with careful positioning protects patients more effectively.

X-rays during pregnancy

Tell the dentist if you are or might be pregnant. The ADA states that studies of pregnant patients have affirmed the safety of dental treatment, and its 2024 shielding recommendation applies to all patients, pregnancy included. An X-ray needed to diagnose pain, swelling, infection or injury should not be postponed, because an untreated dental infection is the greater risk. See the pregnancy dental care guide.

Digital X-rays and what to ask your dentist

Most dental X-rays are now digital: a small sensor or phosphor plate replaces film, and the image appears on screen within seconds. It can be enlarged, stored and sent to another dentist without a retake. The ADA and FDA guidance notes that digital imaging offers a further 40 to 60 per cent dose reduction compared with film.

Questions to ask:

• Which images are you recommending, and what are you looking for?
• How often do I need them at my level of risk?
• Can you use recent X-rays from my previous dentist?

X-rays are usually part of an examination: a dental exam with X-rays typically costs AED 300–600, and the pricing page lists other treatments.

Practical decision guide

General dental decisions should preserve healthy tooth structure whenever possible. A good plan moves from diagnosis to the least-invasive durable treatment, then to prevention so the same problem does not repeat.

Check this first

• X-rays, pulp vitality, crack lines, gum pocketing, bite contacts, and how much natural tooth remains.
• Whether the problem is active disease, old restoration failure, trauma, wear, or a cosmetic concern.
• Whether a filling, onlay, crown, root canal, extraction, or monitoring is the right next step.

When to book sooner

• Pain wakes you at night, lingers after hot or cold, hurts on biting, or comes with swelling.
• A crown or filling falls out, a tooth cracks, or a sharp edge is cutting the tongue or cheek.
• You notice pus, fever, spreading swelling, or difficulty opening, swallowing, or breathing.

Questions to ask at the appointment

• What is the diagnosis, and what evidence supports it on the x-ray or clinical exam?
• What is the smallest treatment that solves the problem predictably?
• What failure signs should I watch for after treatment?

Dubai patient note

If insurance is involved, ask whether pre-approval is required, what codes will be submitted, and what alternatives are clinically acceptable if coverage is limited.